Composite structure



Patented July 12, 1927.

UNITED STATES PATENT OFFICE.

FRANCIS G. OKIE, 0] ST. PAUL, MINNESOTA, ASSIGNORTO MINNESOTA & MANUFACTURING COMPANY, OF ST. PAUL, MINNESOTA, A. CORPORATION OII' COMPOSITE STRUCTURE.

No Drawing.

My present invention relates in general to. the treatment of material preferably in sheet form, and more particu arly the treatment of material'for the purpose of forming or attaining composite structures, of which well known forms of abrasives such as what is commonly known as sand-paper is an example. The present application is in part a continuation and in part a division of my co-pending applications Serial Nos. 428,287 and 428,289 filed December 4, 1920, and 541,248 filed March 4, 1922, and my Patent- Number 1,565,028.

Although I hereinafter disclose the practice of my invention in connection with abrasivcs such as sand-paper, it will be understood that my invention, or certain features thereof, has a Wider field of utility.

Composite structures of the abrasive type such as sand-paper or emery cloth comprise generally (a) a base of sheet material, which may be felted as in the case of paper or woven as in the case of cloth, (1)) a more or less finely comminuted resistant material having abrading properties, such as garnet or corundum, and (c) :a binder generally in the form of a glue which serves to bind the abrasive to the base.

The abrasive products as produced at present have as incidents certain features among which are affinity for moisture rendering them substantially inutile in the presence of water or moisture, and cracking, with consequent exposure of the base, when bent.

The principal objects of my present invention are the provision of a binder which functions more efiiciently than an known to me; the provision of a binder c aracterizedby flexibility without cracking or other undesirable effects; the rovision of a binder characterized by extensl ilit and compressibility to accommodate itse f to flexion of the base; the provision of a binder by means of which the desired adhesive action between it and the base is attained not only efiiciently but also with a desirable degree of acceleration, and more particularly the provision of a binder in which the drying action will be effective from the contact surface between it and the base outwardly; the provision of a binder in which the drying action will be Application filed October 24, 1923. Serial No. 870,548.

efi'ective from the outer surface inwardl the provision of a binder characterized y a drying action that permits of handlin the product with a minimum of dela an more particularl such handlin without impairment of t e superficies 0% the material; the provision of a binder characterized by an accelerated drying actionthe provision of a, binder characterized b a. limitation of its drying action; the provision of an improved moisture-proofing treatment for material, and especially material in a sheet form, and more particularly for causing a moisture proofing agent to penetrate into the material; the provision of a moisture-proof composite abrasive structure; the provision of a binder having moistureproofing functions, and the provision generally of an improved composite abrasive structure and of a method of producing the same, together with such other objects and additional benefits and advantages as may hereinafter appear or be pointed out.

In the employment of my present invention for the production of sand-paper and the like (which I cite for purposes of example) I use as the base a sheet of material (which may be paper or cellulose, or paper or cloth saturated or partly saturated with cellulose or the like) as will conveniently serve the employment contemplated, and as the abrasive such comminuted material (which may be crushed garnet) similarly adapted to serve the function in view.

It is desirable that the binder utilized have the functions and characteristics not only of great mechanical strength and of great binding strength, but also that it be non-hygroscopic, permeative, moisture resistant, easily worked, readily obtainable, inexpensive and facilely applied.

I have discovered that ms of such types as rosin are peculiarly a apted for the attainment of these ends, and ordinary turpentine rosin is preferred by me as best attaining the desired end, viewed from certain aspects. Other gums and resins, natural or synthetic, having the desired characteristics may also be utilized.

In preparing the binder for use, the gum is used in connection with a suitable vehicle which I prefer is of a type such as example, China wood oil orany similar drying oil or semi-drying oil.

This results in a moisture-proofing of the material even against the absorption of moisture through the surface opposite to that to which the binder is applied, without at the same time defacing or otherwise 'undesirably affecting such opposite surface.

This penetration by the vehicle, particularly when coupled with the use of the character of gum pointed out above, carries with it in such penetration a certain amount of finely divided gum so that a coating and binding action is secured between the fibres a base .of..paper, for example, I have association in the binder with the borate of manganese it intensifies the action of the binder in holding the abrasive firmly against of elemental portions of the base which thus.

substantially retards, if it does not entirely prevent, disintegration of the material of the base, in addition to preventing access of moisture through the base to the plane of contact between the base and the main mass of the binder material.

The eflicient action of the binder may be enhanced in the manufacture of sand-paper if the binder is applied to the base by the use of pressure and the more or less finely divided abrasive is then applied in such a manner as to cause it to adhere to the binder.

In order to accelerate the adhesion between the binder and the base, I have discovered it desirable to use with the binder a modifying agent the action of which is to cause a desiccation of the binder initiated at the contact surface of the binder with the base and effective outwardly.

In my experience I have discovered that there are a number of materials having a metallic'base which are useful for my present purposes, that manganic oxides are peculiarly useful and that borate of manganese best combines siccative energy with the desirable susce tibility to fine grinding.

Due to tli binders enerally, difliculties are encountered in hantfiing the structure, within a convenient period because of the soft and sticky character particularly of the exposed surfaces of the binder. This objection I mitigate by associating with the improved binder a substance the action of which is to produce an accelerated drying action effective primarily at the exposed surface and working inwardly, and for this purpose I incorporate in the binder a modifying element peculiarly effective in its action as anoxidizing agent e relatively slow drying of the base.

For intensifying the binding action of the binder and for intensifying the drying ac tion of the dryers, and at the same time accon'lplishin'g such ends by the employment of a material .which is efiicacious in holding the mineral elements in suspension without loss of siccative energy or reducing the relative fluidity of thematerial I have discovered that it is advantageous to employ as part of the binder a paste dryer. This may comprise such mineral substances as sugar of lead and borate of manganese suspended in a resinous vehicle but I find it preferable to form the. paste dryer so as to have the minerals contained therein in the form of acetate of lead and resinate of manganese. I have found by experience that the paste dryer should be somewhat in the nature of cheesy butter, rather softer, and bf a light brownish grey color. I

As an auxiliary in (1) accentuating the adhesion of the binder to the paper, (2)

facilitating to a certain extent the spreading of the binder, and (3) modifying as desired the consistency of the binder as is useful in cases where it is, desired to render it more fluid, I have discovered that the use of a japan dryer is desirable. Such a dryer as that known as Schrack japan is convenient. One form of this contains shellac, red lead, litharge, manganese oxid, burnt umber, gum, linseed oil and turpentine q. s.

In order to give the binder the desired body volumetrically considered I preferably employ a varnish consisting largel of China-wood oil, linseed oil, Perilla Oll, or

fish oil, boiled until it approaches a solid state; As far as feasible this should be as free as possible from glycerides and fatty acids.

Though I have hereinabove disclosed certain forms of useful dryers having various characteristics. and likewise intensifiers, I have discovered that where it is advisable that the siccative action thereof be limited, or at least retarded, under certain conditions, or when producing material for certain purposes, that it is desirable to incorporate Ill) i .in the binder a non-drying oil such as castor oil or the like, for such purposes.

Sand-paper made in accordance with the disclosure of my present invention is characterized by great flexibility without any adverse effects, such as cracking of the binder or base, or loosening of vone'froni the other.

Due to the character of binder for sandpaper and the like which I thus produce, the ad esion between the base, binder and abrasive is such that an auxiliary bonding material, such as the outermost or top sizing coat, customarily found necessary, may for some purposes be dispensed with,.but may be applied for, other purposes. Additionally, the nature of thebond between the base binder and abrasiveiss'uch that sand-paper roduced according to my present invention 1s. characterized by greater freedom from clogging when used on varnished and analogous surfaces.

In cases where it is desirable or necessary to employ a sizing coat, I find that a thinned composition similar to that disclosed herein as forming the binder itself, is satisfactory.

As an example of the sizing coat, which also may be employed as a moisture-proof backing, I submit the following formula by weight: I p

v A Treated rosin or resin 2700. Chinawood oil j 13962 Mineral dryers 79 Thinners 12611- An alternative formula for the same purpose may include the following ingredients yweight:

Treated rosin or resin 2700 Chinawood oil 8100 Mineral dryer 83 Linseed oil 2125 Thinners 8850 The materials used by me as hereinabove described may be varied in character'so as to vary the characteristics of the binder from the stand-point of adhesiveness, non-hygroscopic, and flexibility. Where such variation in the use of materials is employed to produce, for instance, increased adhesion between the binder and the abrasive, such increase'may be attained though possibly at a certain expense in its characteristic of flexibility. Due, however, to this very same increased adhesiveness, one or more of the outer layers of the base may be remoyed as by the employment of a base which involves the use of a built up structure having a number of plies, certain of which may be removed, or by shaving off part of the thickness of the base, or by splitting an ordinary sheet of paper. This is made possible-in the case of my improved binder since I am able to regulate the degree of its penetration of the paper, as desired, and so, after soaking,

Hardened rosin 24 lbs. 12% Linseed 'oil 20 lbs. 10% Dryer 2lbs. 1% Thlnner, say l 48 lbs. 24%

One of the virtues of a waterproof binder of the present composition is that it not only penetrates the supporting base, rendering it waterproof, but also is of great utility as contrasted with organic glue (prepared from gelatinous matter) inasmuch as it may be used with oiled or waxed paper ,which has been waterproofed by treatment with so called ndn-drying oil, such 1 as castor oil, semi-drying oil, such as soya-bean oil, or even drying oil such as .linseed oil, or China wood oil, or fish oil, waxy compounds, suchas araflin, beeswax, carnauba wax, etc., to which a glue bond will not adhere; but to whichmy improved binder readily by virtue of its powers of permeatmn of the base and of commingling with such oiling, greasing or waxingagents. In practice I not only find it convenient to heat the binder to facilitate its application to the back, but alsoto increase its powers of penetration of the base.

- After the adhesive and abrasive materials are applied, the paper is suitably forced dried (or partially baked as it is said), to the desired extent by subjecting it in the usual manner to a temperature which I refer to control between 130 F. and 150 dependingupon the degree of hardness desired, an average of say 140 F. being inmy opinion the optimum, a suitable degree of humidity being-maintained in the drying chamber-to prevent the paper from becom-- ing too crisp or brittle. I

The binder of my present invention is noteworthy in that itnot only penetrates the paperetc. of the backing or base, but penetrates, mixes with, or combineswith various oils, greases and waxes that arecommonly used as waterproofing agents for fabric, and this without weakening, breaking down, or

adheres I China wood oil (tung, oil) 106 lbs. 53%

other, deleterious mechanical or chemical efiects. I V

In cases where the surface of the fabric is not suitable forthe application of a smooth coating of the binder I have found it convenient to apply a filler to the base to facilitate such application. This may consist of an one of the known fillers having a clayey, siliceous, or like base.

Having thus described my invention and illustrated its use, what I claim as new and desire to secure by Letters Patent is 1. The new article of manufacture in the nature of sandpaper, comprising a flexible sheet of fabric, a grit or layer of abrasive articles, and a waterproof stable adhesive 0nd, including modified Chinawood oil inter osed between said grit and said sheet an of a nature to adequately maintain its bonding effect in substantially full measure throughout the efl'ective abrading life of the abrasive article even under sustained application of or immersion in water, but not deleteriously affecting the flexibility of said sheet when dry.

2. Thenew article of manufacture in the nature of sandpaper, comprising a flexible sheet offabric, a grit or layer of abrasive particles and a waterproof stable adhesive bond, including Chinawood oil and rosin interposed between said grit and said sheet and of a nature to adequately maintain its bondin effect in substantially full measure throng out the effective abrading life of the abrasive article even under sustained application of or immersion in water, but not deleteriously affecting the flexibility of said sheet when dry.

3. The new article of manufacture in the nature of sandpaper, comprising a flexible sheet of fabric, a grit or layer of abrasive particles, and waterproof stable adhesive 0nd, including Chinawood oil, treated rosin, and linseed oil interposed between said grit and said sheet and of a nature to adequately maintain its bonding effect in substantially full measure throughout the effective abrading life of the abrasive article even under sustained application of or immersion in water, but not deleteriously afoil gecting the flexibility of said sheet when 4. The new article of manufacture in the nature of sandpaper, comprising a flexible sheet of fabric, a grit or layer of abrasive particles, and waterproof stable adhesive ond, including Chinawood oil, treated rosin, linseed oil and a dryer interposed between said grit and said sheet and of a nature to adequately maintain its bonding eftectin substantially full measure throughout the effective abrading life of the abrasive arti ole even under sustained application of or immersion in water, but not deleteriously affecting the flexibility of said sheet when dry.

5. The new article of manufacture in the nature of sandpaper, comprising a flexible sheet of fabric, which is moisture-proof, a grit or layer of abrasive particles, and a nesaeor waterproof stable adhesive bond, including a Chinawood oil, rosin and linseed oil interposed between said grit and said sheet and penetrating the latter and of a nature to adequately maintain its bonding effect in substantially. full measure throughout the of fective abrading life of the abrasive article even under sustained application of or immersion in water, .but not deleteriously affecting the flexibility of said sheet when dry.

6. The new article of manufacture in the nature of sandpaper, comprising a flexible sheet of fabric, which is moisture-proof, a.

7. The new article of manufacture in the nature of sandpaper comprising a flexible sheet of fabric which contains a moistureproofing oil, a grit or layer of abrasive particles and a waterproof stable adhesive bond, including Chinawood oil and a modifying agent therefor interposed between said grit and said sheet and penetrating the latter and uniting with said moisture-proofing oil and of anature to adequately maintain its bonding effect in substantially full measure throughout the effective abrading life of the abrasive article even under sustained application of or immersion in water but not deleteriously affecting the flexibility of said sheet when dry.

8. The new article of manufacture in the nature of sandpaper comprising a flexible sheet of fabric, a grit or layer of abrasive particles, and a waterproof stable adhesive bond, including rosin and a drying oil for rendering same flexible when dry interposed between said grit and said sheet and of a nature to adequately maintain its bonding effect in substantially full measure through out the effective abrading life of the abrasive article even under sustained application of or immersion in water, but not deleteriously affecting the flexibility of said sheet when dry.

9. The method of forming an abrasive article in the nature of sandpaper or the like which includes impregnating a suitable flexible sheet of fabric with a water-insoluble oil, and applying a grit or layer of abrasive particles to said sheet by interposing a coat of waterproof binder material, which is flexible when dry, containing an oil misciblewith the oil of said sheet whereby to attach "impermeable by Water.

10. The method of forming an abrasive a article in the nature of sandpaper which includes as steps thereof, the application to a flexible sheet of'fabric of a grit or layer of abrasive particles, by interposing a coat of waterproof material as a stable waterproof adhesive bond between said grit and one surface of said sheet, which'is of a nature when dry to maintain the bonding effect throughout the effective abrading life of the abrasive article even under sustained application of or immersion in water, and hastening solidification of said adhesive by the application of heat without deleteriously affecting the flexibility of the article.

11. The method of forming an abrasive v article in the nature of sandpaper which includes as steps thereof, the application-to a flexible sheet of fabric, of a grit or layer of abrasive particles, by interposing a coat of waterproof material as a stable waterproof adhesive bond between said grit and one surface of said sheet and allowing said materialto penetrate the" sheet, and said adhesive being of a nature when dry to maintain the bonding effect throughout the ef fective abrading life of the abrasive article even under sustained application of or immersion in water,'and solidifying said adhesive by the application of heat without deleteriously affecting the flexibility of the article.

.12. The method of forming an abrasive article in the nature of sandpa er which includes as stepsthereof, the app ication to a flexible sheet of fabric which includes therein a moisture-proofing agent, of a grit or layer of abrasive particles by interposing a coat of waterproof material as a stabl e waterproof adhesive bond between sa d gut and one surface of said sheet, and allowing said material to penetrate the sheet and unite with the moisture-proofing agent, sald adhesive and agent being of a 'nature when dry to maintain .the bonding effect throughout the effective abrading life of the abrasive article even under sustained ap lication of or immersion in water, and soil ifying said adhesive b the application of heat without deleterious y affecting the flexibihty of the article. 1 ti;

13. l he method of forming an abrasive article in the nature of sandpaper which includes-as steps thereof, the application to a flexible sheet of fabric which includes therein a water-insoluble wax or oil, of a gut or layer of abrasive particles by interposing a coat of waterproof materlal as a stable water proof adhesivebond between sald r1t and one surface of said sheet, allowing sald material to penetrate the sheet and unite with such waterinsoluble wax or oil, said bond being of a nature when dry to maintain the bonding effect throughout the effective abrading life of the abrasive article even under sustained application of or immersion in water, and hastening solidification of said adhesive by the application of heat without deleteriously afiecting the flexibility of the" article.

14. The method of forming an abrasive article in the nature of sandpaper which includes as steps thereof, the application to a flexible sheet of fabric which includes therein a moisture-proofing agent, of a grit or layer of abrasive particles by interposing a coat of waterproof material containingan oil and a resin as a stable waterproof adhesive bond between said grit and one surface of said sheet and allowing said material to penetrate the sheet and unite with such moisture-proofing agent said oil and said agent being of a nature when dry to maintain the bonding effect throughout the effective abrading life of the abrasive article even under sustained application of or immersion in water, and hastening solidification said adhesive by the application of heat without deleteriously affecting the flexibility of the article. k

15. The method of forming an abrasive article in the nature of sandpaper which includes as steps thereof, the treatment of a flexible sheet of fabric with a water-proofing substance which enters the sheet, applying "a grit or layer of abrasive particles to said sheet by interposing a coat of waterproof material as a stable waterproof adhesive bond between said grit and one surface of said sheet, allowing said adhesive to penetrate the sheet to unite with the waterproof substance thereof, said bond being of a nature to maintain the bonding effect throughout the effective abrading life of the article, and hastening solidification of said adhesive by the application of heat at a predetermined temperature.

16. The method of producing flexible abrasive material which comprises associating a suitable base with a coating of a varnish containing an abrasive and heating the same to a temperature about 140 F.

17 The method of producing flexible abrasive sheet material comprising associa- China wood oil varnish in the form of a coat-' ing containing an abrasive material and heating to a temperature about 140 F.

18. The method of forming an abrasive article in the nature of sandpaper which includes as steps thereof, the application to a flexible sheet of fabric contaming a waterproofing agent, of a grit or layer of abrasive particles, by interposing a coat of waterproof material as a stable waterproof adhesive bond between said grit andone surface of said sheet, which is of a nature to unite with said waterprcofing agent, and when dry to maintain the bondin efiect throughout the efiective life of the a rasive article even under sustained application of or immersion in water, and hastening solidification of said adhesive by the application. of heat without deleteriously affecting the flexibility of the article.

19. A new abrasive article in the nature of sandpaper which includes a flexible sheet of fabric, a grit or layer of abrasive parneeaaoi article even under sustained application of or immersion in water,

In testimony whereof I have hereunto signed my name.

' FRANCIS G. OKIE. 

